The present invention relates to a nitride semiconductor device using nitride semiconductors for active layers and a process for producing thereof, and specifically, relates to a nitride semiconductor device which is making Schottky contact with a semiconductor device such as a High Electron Mobility Transistor (HEMT) and a Field Effect Transistor (FET) and a process for producing thereof.
FIG. 10 shows the cross-section view of a semiconductor device comprising a conventional III-V Group nitride semiconductor. The semiconductor device shown in FIG. 10 shows a so-called HEMT structure and it is a structure in which a buffer layer 102 consisting of gallium nitride (GaN), a channel layer 103 consisting of gallium nitride, a charge supply layer 104 consisting of n-type aluminum gallium nitride (AlGaN) and a Schottky layer 105 consisting of non-doped aluminum gallium nitride were deposited in order on a substrate 101 consisting of a sapphire substrate. Two dimensional electron gas having extremely high electron mobility consisting of a potential well is formed nearby a hetero junction interface consisting of the channel layer 103 and the charge supply layer 104. The semiconductor device having such structure controls carrier density of two dimensional electron gas which flows between a source electrode 107a and a drain electrode 107b by controlling voltage which is applied to a gate electrode 106 (control electrode) making Schottky contact with a Schottky layer 105.
Various structures which are disclosed in, for example, Japanese Unexamined Patent Publication No. 335637/1998 are proposed for this kind of semiconductor device, in addition to the above-mentioned structure.